I went through a similar journey not too long ago. I also asked myself "Why does highlighting even need to be in color?" when reworking my blog. I wanted a monochromatic look for my entire site, including code blocks. I noticed code blocks are still very readable as long as there's different tones. I still like pretty colors so I compromised by doing normal syntax highlighting when a code block is hovered over (or tapped on mobile).

Btw the dynamic highlighting by clicking on the code is so cool. I may or may not steal that idea ;)